Method of forming cams



Sept. 24, 1929. F. TERBUSH METHOD OF FORMING CAMS Original Filed July 26, 1924 Eng. 6.

Patented Sept. 24, 1929 UNITED STATES PATENT OFFICE FLOYD TERBUSH, OF ROCHESTER, NEW YORK, ASSIGNOR TO NORTH EAST ELECTRIC COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK METHOD OF FORMING CAMS Application filed July 26, 1924, Serial No. 728,508. Renewed February 28, 1929.

In certain power-mechanisms, for use in.

actuatin' typewriters and the like, it has been proposed to use cams which are driven by engagement with a rubber-covered roller and 5 which have to be started, rotated and stopped in very short intervals of time.

For the sake of lightness and of economy in manufacture, it is desirable to make suc camsof sheet-metal, and they may be drawn .0 in cup-like form, comprising a web or body surrounded by a flange which provides the working-face of the cam. A further important requisite, however, is that the maximum possible width of working-face be given to .5 the cam, since this width will, In any case, be small owing to the limitations of space within the machine. To this end it is desirable that the web and the flange be joined at a sharper or more nearly exact right angle than can be produced in an ordinary drawing operation.

The present method comprises a series of operations by which a cam is made of sheetmetal with a serrated working-face of a 15 width equal to the full width of the flange, and with the edge of the flange accurately formed and finished, including one or more of the stop-lugs or the like which may project integrally from the flange.

0 The invention is illustrated in the accompanying drawings, in which Fig. 1 is a sideelevation of a cam formed in accordance with the novel method; Fig. 2 is a section on the line 2-2 in Fig. 1; Fig. 3 is an outline View of the sheet-metal blank from which the cam is drawn; Fig. 4 shows the sheetmetal cup in section, after the drawing operation; Fig. 5 is a sectional view showing the final upsetting operation on the flange; and

Fig. 6 is a side-elevation-of the punch by which the u setting operation is performed. A form 0 cam which may be made by the present method is shown, in Figs. 1 and 2,

as comprising a web-portion 10 and a periph- 5 eral flange 11. The flange has two convex serrated portions 12 constituting the working faces of the cam. Two stop-lugs 13 project integrally from the edge of the flange 11. The web is shown as somewhat cut away for the sake of lightness, but this is of no consequence in connection with the present Invention.

In forming a cam like that of Figs. 1 and 2 by the present method, a suitable blank 14 of sheet-metal is first punched, this blank being provided with two projections 15 to furnish the material for the stop-lugs. The blank is then drawn into the form of a shallow cup, of the required outline, as shown in Fig. 4. In this operation the web and the flange are formed, but they are united by a smooth curved ortion of the sheet-metal, as it is impracticable to form a sharp angle at this point in the operation of drawing the sheetmetal.

The flange of the cup, as drawn, is of irregular width, the irregularities being such as have been found, by experiment, to be necessary to provide the stock necessary, at different points, to complete the cam in the final pressing operation.

The next operation consists in subjecting the cup to an edgewise pressure applied to the flange while the cup is supported in a suitable die 16. The punch 17 used for this purpose has a projection 18 which fits closely against the inner surface of the flange, and a shoulder 19 which rests against the edge of the flange, the shoulder being recessed at 20 to receive and form the lug or lugs 13. The die 16 fits closely against the out-er surface of the flange, and is formed with a sharp right-angle between its sides and bottom.

When the cup is pressed between these tools the curved metal between the flange and the bottom is forced down into the angle of the die so as to assume the form shown in Fig. 6. At the same time the lugs 13 and the edge of the flange are accurately formed by the pressure.

The final operation of the present method consists in cutting the teeth across the flange, which may be done by milling, broaching or in any convenient way.

The invention claimed is:

1. The method of making a cam which con sists in drawing a cup of sheetanetal with a lug on the edge thereof subjecting the cup to, edgewise pressure, by a'punchconforming to the edge of the cup including the lug thereon,

within a die having a sharp angle between the bottom and the sides whereby the sheet-metal is forced into said angle and given. a sharp right-angular form between the web and the flange of the cam; and thereafter cutting teeth across the flange of the cam.

2. The method of making a non-circular cam, which consists in drawing, from sheetmetal, a cup of the required outline having an irregular edge, confining the cup Within a die of the same outline and of greater depth than the cup, with a sharp an le between the bottom and the sides, and subJecting the cup, within the die, to pressure from a punch which fits closely the inner surfaces of the cup and of the die cavity, With a shoulder of the form required for the edge of the cam, whereby the metal of the cup is flowed into the lower angle of the die and also against said shoulder, thus forming, at one operation, a finished edge and a sharp lower angle on the cup.

3. The method of making a non-circular cam, which consists in cutting a non-circular blankwith :1 lug projecting from the edge thereof, drawing the blank into a non-circular cup with the lu; projecting from and in the plane of the side wall thereof, confining the cup within a die of the same outline and of greater depth than the cup, with a sharp angle between the bottom and the sides, and

subjecting the cup, Within the die, to pressure from a punch which fits closely the inner surfares of the cup and of the die cavity and has a shoulder, for forming the edge of the cam. provided with a recess to receive and form the lug, whereby in a single operation the metal of the cup is flowed into the lower angle of the die and a finished form is given to the edge and the lug.

' FLOYD TERBUSH. 

